^ fing02.gif I use parts express for end item parts alot of the time. I never think of them when it's time to order component parts.



PartsExpress.com is a great site. Try there, and if your friend hasn't seen it yet, www.Mouser.com "engineered for engineers". They have just about any specialty thing you'll need to build just about anything you can immagine.

Radio Shack is too darn expensive for any type of large scale project. They will charge you $1 for 5 resistors. You should be paying $1 for 50 resistors. You can just specify the type of resistor and they make you pay like $2 extra for 500 resistors of a different type then 470 ohm when you buy LEDs w/ resistors.

You can always double and tripple up on LEDs in series until the total resistance needed by the LED string is less then the resistance provided by the resistor. 2 Blue LEDs will usually require a 470 ohm resistor or higher. You've got to find a resistor with a value at or above the resistance value you require.

OH, another trick, You can add .7 to the foreward bias value by adding a standard diode in series.

In what field of engineering is your friend? I am an electronics tech. Basically, it's my job to maintain what the electronics engineers make and assist in making changes.

....oh, btw... the reason i mentioned the .7 diode thing, is by adding 2 diodes to the red LEDs, they basically assume a higher FV value then a blue LED. Which means you could just get 1 type of resistor and run the red LED at like .15mA instead of .20(max)


... dang, someone change the topic to "everything you need to know about LEDs or something" laugh.gif

 

Wow, that mouser site is amazing! (although you kinda have to know exactly what you want)


I saw some superbrightleds had diodes inside in series with the LED, I wondered why (I assumed maybe to prevent damage to the LED when it's wired the wrong way) Could you explain this a little more? I don't understand how it works.. in my mind a perfect diode is just something with 0 resistance if the current is going the right way or infinite resistance if its going the other way.. am I oversimplifying?

Edit: I just read about diodes on wikipedia and I think I got it now smile.gif Afterall, it's just like putting another (smaller) LED in series, except it doesn't light up smile.gif

 

it takes .7V to overcome the foreward bias of most diodes. Just like it takes 3.5V to overcome the foreward bias of a blue LED. This voltage is actually removed from the circuit. Diodes chop actual voltage, resistors disapate current which drops total wattage and makes less potential for voltage.

There IS some power usage by a diode, but we don't really factor that in. It's very very small, same as a LED.

Here's the cool part. Foreward bias > resistance. If you could regulate the voltage input, then use a series of LEDs and diodes to match the 14.6V, you could have a total power usage of like .01W on a 1ohm resistor. Resistors are parasitic in a silicone circuit.

 

yeah this thread is probably one of the first in its kind!! my friend is doing mechanical engineering but in poland they teach them a lot of techno electro stuff as well. that and he likes to take things apart.

should i shave the top of the blue leds down and glue them face first into the stencil material? how is the best way to go about that?

see all these little details we don't know about.

 

Shaving the LEDs diffuses the light, so instead of it being a point light, it's all around. Definitely do it.

 

wholy cow everything works great! umm except we've got to add some more reds to the needles because you have to stick some right in there to light them up around all rpms.

it looks great on the F2 gauges!!! never thought we'de get finished. blew one blue led because the - + touched and were accidently glued together... he he he.

another week and i'll have some photos. we did things a lot different than usual, instead of drilling holes and gluing the led's into the clear plastic, we attached them to a plastic platform in the back. it was sprayed chrome so it reflects all the light like a flashlight. it's bright as hell!!

i also used nail polish for the needles. they sparkle. p i m p.

thanks to you guys who have helped me, and tibby01/dtn for the DIY.

 

postpics.gif

 

well good news and bad news. bad news: they sent 5mm instead of 3mm and i had to get the car back together today because my dad's car is in the shop with a crap alternator.

so we fit the 5mm in for the needle lighting and accidently broke some of the metal on the needle motor.

so do i have to order a whole new gauge? what to do about the needle motors?

 

Which motor? I have a set of gauges here I can send parts.

 

oh hell yes adam!

the two left ones, rpm & speedo. but i don't know if they come off at all.

man that's the only thing wrong with it, other than that everything looks great.